The revised competing renewal proposes continuation of three ongoing projects and one new project directed towards fundamental processes of Alzheimer;s Disease (AD). Overall, our emphasis is on cytoskeletal abnormalities, which we hypothesize to be both the proximate cause of dementia in AD, and of primary importance to the progression of this disease. Of the four projects, there have as their starting point abnormal neuronal filaments in the AD and non-AD brain, and one remains focused on amyloid deposition and plaque formation in relation to neuritic pathology. The first project will continue studies of proteins involved in paired helical filament formation, identified with a now considerable panel of monoclonal antibodies. Previous work on the purification and characterization of paired helical filament proteins will be extended with a new and efficient method for the purification of soluble PHF. Our findings have led to a new understanding of a protein kinase activity associated with these structures. Continued studies with new monoclonal antibodies will attempt to identify two intriguing epitopes. Limited studies will attempt to correlate specific biochemical abnormalities in Alzheimer's Disease with Braak's pathological staging scheme. The second project will continue studies of MAP2, especially of expression and possible function of 5 new exons discovered in the last project period. Tissue and cell culture studies will define the developmental expression of both the mRNAs and proteins containing these exon sequences, the effects of disrupting their expression, and possible alterations in expression in AD and diffuse Lewy body disease (DLBD). The third project will continue studies of senile plaques in AD, pathologic aging and DLBD, especially with regard to glycation, association of ApoE with amyloid, glial activation and the influence of neuritic pathology on the nature of these processes. Cell biologic and biochemical studies of protein glycation will also be undertaken. The fourth project will expand on work from the last project period that has revealed that several phosphoepitopes characteristic of the AD brain are present in neuroblastoma cells at specific times during mitosis. Studies are planned to identify one of these mitotic antigens and to identify the kinase responsible for the production of this epitope in both MSN cells and in brain. The possibility that inappropriate activation of cell division mechanisms occurs in the AD brain will be explored.